Chapter 11 Antivirus control

type must be added to the end of the list (the Skip all other files rule is predefined for this purpose).

11.4 Email scanning

SMTP and POP3 protocols scanning settings are defined through this tab. If scanning is enabled for at least one of these protocols, all attachments of transmitted messages are scanned.

Individual attachments of transmitted messages are saved in a temporary directory on the local disk. When downloaded completely, the files are scanned for viruses. If no virus is found, the attachment is added to the message again. If a virus is detected, the attachment is replaced by a notice informing about the virus found.

Note: Warning messages can also be sent to specified email addresses (e.g. to network administrators) when a virus is detected. For details, refer to chapter 17.3.

Warning:

1.Antivirus control within WinRoute can only detect and block infected attachments. Attached files cannot be healed by this control!

2.Within antivirus scanning, it is possible to remove only infected attachments, entire email messages cannot be dropped. This is caused by the fact that the firewall cannot handle email messages like mailservers do. It only maintains network traffic coming through. In most cases, removal of an entire message would lead to a failure in communication with the server and the client might attempt to send/download the message once again. Thus, one infected message might block sending/reception of any other (legal) mail.

3.In case of SMTP protocol, only incoming traffic is checked (i.e. traffic from the In- ternet to the local network — incoming email at the local SMTP server). Checks of outgoing SMTP traffic (i.e. from the local network to the Internet) might cause problems with temporarily undeliverable email (for example in cases where the des- tination SMTP server uses so called greylisting).

To check also outgoing traffic (e.g. when local clients connect to an SMTP server without the local network), define a corresponding traffic rule using the SMTP pro- tocol inspector. For details, see chapter 11.2.

Advanced parameters and actions that will be taken when a virus is detected can be set in the Email scanning tab.

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Kerio Tech Firewall6 manual Email scanning, 170